class VersionedArray extends Array {
  constructor() {
    super();
    this.history = [[]];
  }
  commit() {
    this.history.push(this.slice());
  }
  revert() {
    this.splice(0, this.length, ...this.history.pop());
   
  }
  print(){
      for(let i=0;i<this.length;i++){
          console.log(this[i]);
      }
  }
}
class fa{
  static print(){
    console.log("this is static fa")
  }
}

class son extends fa{

}



module.exports.VersionedArray=VersionedArray;
module.exports.son=son;

